If equal amounts of water are repeatedly added to an acidic solution, what change is expected?

Correct answer: pH will gradually increase

Dilution decreases the concentration of hydronium ions in an acidic solution. Since pH = −log[H₃O⁺], a decrease in hydronium concentration produces an increase in pH, although the solution may remain acidic for some time. Repeated equal additions of water continue to dilute it, so the pH moves upward toward 7 rather than downward. Therefore option C is correct; the other choices violate the pH concept.